Mikhail Gorbachev, former Soviet president who took down the Iron Curtain, dies

Mikhail Gorbachev -- the last leader of the former Soviet Union from 1985 until 1991 -- has died at the age of 91.

Gorbachev died after a long illness, Russian state news agencies reported.

"Mikhail Sergeevich Gorbachev died this evening after a severe and prolonged illness," the Central Clinical Hospital said, according to RIA Novosti Tuesday.

The man credited with introducing key political and economic reforms to the USSR and helping to end the Cold War had been in failing health for some time.

Russian President Vladimir Putin expressed his condolences, Putin's spokesman, Dmitry Peskov, told RIA Novosti.

Putin will send a message on Wednesday to Gorbachev's family and friends, RIA Novosti added.